Cylinder with variable stop mechanism



Feb. 23, 1954 J. H. cRoss CYLINDER WITH VARIABLE STOP MECHANISM Filed March 28, 1952 mm um Patented Feb. 23, l954 I a'f's'ssn'z?."'` y --CYLINDER wir'n VARIABLE XJnies 'E Cross Application MarchA vlz8. 195g, serial Nov-.marsa 9v claims. (c1. '121.72.13).v v

This invention relates to cylinders. In a more specific aspect it relates to double-acting, expansible, hydraulic cylinders with stopvmechanism incorporated therein, and using the actu'- ating fluid in operating the stop mechanism.

Hydraulic cylinders are used extensively on -industrialmachinery, farm machinery, etc.f They are used to raise and lower plows, such as oneway disk plows, chisel plows, disk angling plows,

and the like, on manure loaders, and the like, for

instance, to regulate the lowest point of descent and to adjust the level of the bucket, on combines to 'level the platform, on land levelers, mowers, sprayers, potato diggers, corn pickers, snow plows, and the like. The tractor hydraulic system is normally used to supply the actuating fluid to the hydraulic cylinder in such uses as are set forth hereinbefore. Hydraulic cylinders are usedv for many lifting, pushing, pulling and adjusting jobs on industrial machinery and equipment. i'

In such uses in many cases, it is desired tofcontrol the stroke, that is to limit the distance the piston canr go on the retracting stroke. For instance, in using a double-acting hydraulic cyl-A inder for raising a plow out of the ground at the end of the iield and lowering it again into Athe ground after the turn has been made, it is desirable that the plow go back into the ground-j each time'to the same depth without having-to adjust the depth each time which takes up valuable time land makes it a matter of guess-workas to whether or not the plow is at the desired depth. Inmany other agricultural and industrial machinery uses of hydraulic cylinders, it is des sirableto provide a stop at some predetermined point in the movement of the piston. Also,`it is desirable that such stop means be adjustable `so that the stop can be set manually or automaticallyto prevent the movement of-the piston" past a desired loaction. Mechanical devices are known in the art which will do this, such devices as an adjustable stop collar and arm attached to the cylinder or a part of the equipment on which thecylinder is used, and separate cylinder means actuated by movement of the rod and/or the cylinder actuating fluid under pressure. The vstop means `knownin the art are not satisfactory-,- being either too complicated and expensive to build, or subject to easily getting out of adjustment. y 'r l I I have invented a very satisfactory expansible hydraulic cylinder with stop mechanism incorpo:

rated therewith. The cylinder actuating uitlvis` cylinder` of .my Ainvention Yis very eflicient, .and easily and cheaply .constructed It :has a 4space formed in the piston rod with a plunger member? extending therein, A.the plunger member being secured to the end'f of the cylinder opposite-'the` end through which. the piston rod. extends. A conduit with a valve therein isformed in the plunger and partly' in the end y ofthe Vcylinder-.to whi'chthe plunger secured. The conduitrv communicates .with the!v space formed in the-'piston rod and the chamberof the cylinderiormed by the piston, the wall' ofthe cylinder and theendto which the plunger issecured. The cylinder and stop mechanism are adapted so that when the "i piston and rod are extendedwith the valve open,

cylinder actuating fluid will flow from-the chamber last-named or from .an-actuating uid supply conduit or chamber, through the conduit and into the space in the piston rod. When the `piston has been extended to the point desired, that is, a point where it isv desired it will stop-on theretraction stroke, the valve is closed, thustrapping the fluid. Then in use the piston and rod will extend-as far as desired, but will only -rei tract to the point desired, since on retraction movement of the piston is preventedby the-.column-of trapped iiuid. When the iiuid is a liquid, relatively non-compressible, the -piston will stop exactly at the desired point. On the extension stroke after thestop has been "set, the partialvacuum formed in the space in the piston rod has been found to cause n o difficulty. To yreadjusi'. and set anew stop point for less retraction the valve is opened' on theextension stroke, letting more fluid flow through the conduit into -the space in the piston rod. To readjust and set a new stop point for greater retraction, the valve is opened on the retraction stroke and fluid in the space in the piston rod is forcedout through the conduit into the cylinder chamber orinto van actuating fluid supply` conduit or chamber. The valve is then closed when the piston reaches the desired` point. The new cylinder of my invention is easy to adjust and exacting in preventing movement of -the piston past a desired and predetermined point. and is, indeed, a great step for- Ward in the artj' It is an object of this invention to provide new cylinder means.

It is another object of this invention to provide new stop mechanism for hydraulic cylinders, utilizing the cylinder aciniatingy fluid in operating the stopl mechanism.

l It is still another objectnof this inventiontopro vide 'aV new A'double-acting, expansiblefhydra-ulic of a hydraulic cylinder, like the one shown in Fig. l, incorporating another preferred specific t embodiment of the stop means of my invention. Fig. 3 is a view taken on line 3-3 of Fig.

2. Fig. 4 is a cross sectional view through vthehead end of a hydraulic cylinder, like the one shown in Fig. 1, incorporating another preferred' v specific embodiment of the stop means of my -invention, wherein the stop mechanism can be adjusted froma point remote from the cylinder, for instance, from a` point near the seat of a tractor..

Following is a discussion of the new hydraulic cylinder of my invention, incorporating the new stop mechanism of my invention. Reference is made to Figs. 1, 2, 3 and 4 of the drawing, and

the same reference numerals are used on all the ngures to indicate the same structure. It is to be understood that the followingv discussion is not to unduly limit the scope of my invention.

Referring now to the drawings, a conventional cylinder 6, held in a suitable manner by head end 8 and rod end ill, has a piston 2 mounted f or reciprocation therein. Bolts 9 with nuts II are very suitable to hold cylinder 6 and end members 8 and I0 together.

Resilient 0 rings i4 pack and seal; so that duid under pressure in the cylinder will not leak out, and resilient O ring I6, the piston ring, packs and seals to prevent leakage of fluid around the piston from the rod end chamber I8 to the head end chamber '20 and vice versa.

. Piston rod- 22 slidably extends through rod end portion I6.

pack and` seal against leakage of fluid from chamber I 8. Conduit 26 threaded into member I0 meets a conduit 28 formed in member I0. Cylinder actuating fluid supplied under pressure, for

instance, from the hydraulic system on a tractor, enters chamber lbyconduits 26 and. 2 8 when it is desired to retract piston I2. Actuating uid leaves chamber I8 by conduits 26v and 26- on the expansion stroke.

Conduit 30 threaded into member 8 communicates with conduit 32 formed in member 8. Cylinder actuating fluid under pressure enters chamber by conduits 30 and 32 on the' expansion stroke, and leaves chamber 2D by conduits 32 and on the retraction stroke.

Piston rod 2'2 has a bore 34 formed therein. A rod 36 with a bore 38 formed therein is secured in a suitable manner to member B and slidably extends into bore 34 in piston rod 22. .A conduit 4.0 is formed in member. 3 which communicates with a smaller conduit v42 in plug 44 which is securedin a suitable manner to member 8 and furnishes the valve seat for valve 46. A needle valveas shown has been found to be very satisfactory. Conduit 48 is formed in member 8 and communicates with chamber 2D. On the expansion stroke of piston I2 with needle valve 46 open cylinder actuating liquid ows from chamber 25 throughconduits 48, 42, 40 and Member I0 is provided with resilient O rings 24 which engage piston 22 and 4 38 into space 50 formed by bore 34 in piston rod 22. Liquid will thus ow until needle valve 46 is closed. On further expansion of piston I2, a partial vacuum will be created in space 50 which Ahas been found to cause no difficulty in operation. On the retraction stroke with valve 46 closed, piston I2 will retract to the point where valve 46 was closed on the expansion stroke, at which point conduit 42 and 4ll,`,b'ore 38 and space 50 will be lled vwith liquidf" and further retraction of piston I2 is prevented.

f Packing gland 52 is threadedly secured to piston. -rod Y22 which extends through piston I2,

andresilient O ring 54 packs and seals against leaking around rod 22 from chamber 20 to chamber I8 and vice versa, and also leakage from and to chamber 56 around rod 36. Bushing 56 fits around rod 36 as shown and provides the end surface against which packing 58 is compressed by packing nut 66 which ts around rod 36 and isthreadedly secured to packing gland 52. Bushing 6,2.flts around rod 36 and provides the other end surface for compression of packing 58. Packing 58 seals againstV leakage either to or from the 4space formed by borer34, bore, conduit 4l)y In the modication of the new cylinder of my invention shown in Figs. 2l and 3, an external conduit. 64 communicating withconduit 40 ink member B is employed instead of conduit 48 shown in Fig. 1. Conduit 64 communicates with aconduit 66 through cylinder 6 into chamber 25. Conduit 64 is suitably attached to valve 46 and cylinder 6. Threaded in attachmenthas been found to be satisfactory.

In the modification of my invention shown in Fig. 4,.valve 46v is located at a point remote from the hydraulic cylinder. Conduit 68 with valve 46 therein communicates with conduit 40. formed in member, and with conduit 36, which supplies cylinder actuating liquid under pressure to chamber ,2D on the expansion stroke and receivesvv actuating liquid from chamber 29]` on the retraction stroke. Conduit 68 canconveniently be flexibletubing. By a point remote from the hydrauliccylinder I mean, for instance, that valve 46 is located n ear the seat of a tractor and the hydraulic cylinder is used on a plow, combine. etc. pulled by the tractor, 0r that Valve 46 is located in a control room and the hydraulic cylinderis used on industrial equipment, and the like.

In operating the stop lmechanism means of my invention, incorporated in the new cylinder of my invention, to adjust so that vpiston I2 will stop at the desired point on the retraction s troke, actuating uid is withdrawn from chamberZl), or conduit 36 (modincation shown in Fig. 4), through valve 46, conduit 46, bore 38 and into chamber 50. Piston I2 is expanded by introducing actuating fluid under pressure into cham,- ber l2D via conduits 30. and 32. Vhen piston I2 has moved to ya pointat which it is desired it will stop on Vthe retraction stroke, valve y46 is closed, preventing further passage of iiuid into chamber 50. The piston I2 .and rod 22 can then be extendedfarther, but on retraction it will not move past the point at which valve 4 6 was closed. To adjust so that the stop point of piston I2 on retraction is nearer member I0, valve 46 is opened on the extension stroke and closed when the piston reaches vthe new stop point.

To adjust so that the stop point is nearer member 8, valve 46,is opened on the rectraction stroke and uid then flows4 from chamber 50 through bore 38, conduit 40. valve 46 and into chamber 2B, or into conduit 30 (modiiication shown in Fig. 4). Valve 46 is closed when piston I2 reaches the point at which it is desired it will stop on the next and subsequent retraction strokes.

As will be evident to those skilled in the art, various modifications of my invention can be made or followed in the light of this disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

Iclaim:

1. An expansible, fluid-pressure operated device with variable stop mechanism, which comprises, in combination, a cylinder and a piston mounted for reciprocation therein, a piston rod connected to said piston and extending through one end of said cylinder, a conduit for supplying fluid under pressure to a chamber in said cylinder adjacent said end of said cylinder, a conduit for supplying fluid under pressure to a chamber in said cylinder adjacent to the other end of said cylinder, a bore formed in said piston rod, a plunger member secured to said lastnamed end of said cylinder and extending into said bore, a conduit with an adjustable valve therein, said last-named conduit formed in said plunger and partly in said last-named end of said cylinder, said last-named conduit communicating with said bore in said piston rod and said last-named chamber, and said last-named conduit closed to the flow of the iiuid into said bore when said valve is closed and adapted to transfer uid from said last-named chamber in said cylinder to said bore on the extension stroke with said valve open and to prevent transfer of fluid from said bore to said last-named chamber in said cylinder on the retracting stroke with said valve closed.

2. The apparatus of claim 1 wherein said lastnamed conduit is wholly within said plunger and said last-named end of said cylinder, and said valve is a needle valve with the valve seat disposed within said last-named end of said cylinder.

3. The apparatus of claim 1 wherein said lastnamed conduit is formed in said plunger and partly in said last-named end of said cylinder and with an external portion, and said valve is a needle valve with the valve seat disposed within said last-named end of said cylinder.

4. The apparatus of claim 1 wherein said lastnamed conduit is formed in said plunger and partly in said last-named end of said cylinder and with an external portion connecting with said second-named conduit, and said valve is disposed in said external portion between said point of connection and said cylinder.

5. A double-acting, expansible, liquid-pressure operated device with variable stop mechanism, which comprises, in combination, a cylindrical member having a head end and a rod end, a piston mounted for reciprocation in said cylindrical member, a piston rod connected to said piston and extending through said rod end. a conduit in said rod end for supplying liquid under pressure to a chamber formed by said rod end, said piston and said cylindrical member, a conduit in said head end for supplying liquid under pressure to a chamber formed by said head end, said piston and said cylindrical member, a bore formed in said piston rod. a plunger secured to said head end and extending into said bore, a single conduit communicating with said bore formed in said plunger and partly in said head end and with an external portion, said conduit communicating between said bore and said chamber formed by said head end, said piston and said cylindrical member, an adjustable valve in said last-named conduit with the valve seat disposed in said portion of said conduit in said head end and the adjusting mechanism disposed external of said head end, and said device adapted to withdraw liquid from said chamber formed by said head end, said piston and said cylindrical member into said lastnamed conduit and bore on the extension stroke with said valve open and until said valve is closed and to prevent retraction past a point at which said valve is closed on said extension stroke.

6. In an expansible Huid-operated device comprising, in combination, a cylinder and a piston mounted for reciprocation therein, a piston rod connected to said piston and extending through one end of said cylinder, a conduit for supplying uid under pressure to a chamber in said cylinder adjacent said end of said cylinder, and a conduit for supplying fluid under pressure to a chamber in said cylinder adjacent the other end of said cylinder, a variable stop mechanism which comprises, in combination, a space formed in said piston rod, a plunger member secured to said last-named end of said cylinder and extending into said space, a conduit with an adjustable valve therein, said conduit formed in said plunger and partly in said last-named end of said cylinder and communicating with said space in said piston rod and said last-named chamber, and said valve disposed at a point in said conduit to prevent now of fluid into said space when said valve is closed.

7. A motor, which comprises, in combination, a housing, a head end mounted on said housing, said head end having a conduit therein, a piston mounted for reciprocation in said housing, a piston rod having a space therein connected to said piston, a conduit member mounted on said head end, said conduit member extending into said space in said piston rod and communicating with said conduit in said head end, a conduit communicating between said conduit in said head end and a chamber formed by said housing, piston and head end, and adjustable valve means mounted in a resulting conduit communicating between said space in said piston rod and said chamber at a point in said resulting conduit to form when closed a sealed space on said piston rod space side of said valve means, said sealed space being separated by said valve means from the portion of said resulting conduit on the chamber side of said valve means.

-8. The apparatus of claim '7 wherein said conduit communicating between said conduit in said head end and said chamber is formed in said head end, and said valve means is mounted in said head end.

9. The apparatus of claim 7 wherein said conduit communicating between said conduit in said head end and said chamber has an external portion and said valve means is mounted in said ex ternal portion.

JAMES H. CROSS.

References Cited in the ille of this patent UNITED STATES PATENTS Number Name Date 649,357 Ridgway i May 8, 1900 2,456,236 Acton Dec. 14 ,1948 

